Die set for shaping a spring strip to predetermined form



y 5, 1959 E.. G. OTT ETAL 2,884,962

DIE SET FOR SHAPING A SPRING STRIP T0 PREDETERMINEQ FORM Filed Dec. 8, 1953 v Sheets- Sheet 1 v INVENTORS. W 15 7713; G, 027. q BYZ'ervzarZ I h d/zz's.

Array/VX145 y 5, 1959 E. G. OTT ETAL 2,884,962

DIE SET FOR SHAPING A SPRING STRIP TO PREDETERMINED FORM Filed Dec. 8, 1953 '7 Sheets-Sheet. 2

. INVENTORS. 1721s? 6 022. fierzzdri J2 1441/7152 BY %mw, *PW' y 5, 1959 E.G\.OTT ETAL 2,884,962

DIE SET FOR SHAPING A SPRING STRIP TO PREDETERMINED FORM Filed Dec. 8, 1953 7 Sheets-Sheet 3 I *2; /Z INVENTORS.

y 5, 959 E. G. on ETA]. 2,884,962

DIE SET FOR SHAPING A SPRING STRIP TO PREDETERMINED FORM Filed Dec. 8, 19 53 7 SheetsSheet 4 )1 v INVENTORS. Irrrsz 6", 02"? Jar-2747'; j

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y 1959 E. c.0151 ETAL 2,884,962

DIE SET FOR SHAPING A SPRING STRIP T0 PREDETERMiNED FORM Filed Dec. 8, 1953 7 Sheets-Sheet 5 y 5, 1959 E. ab ETAL I 2,884,962

DIE SET FOR SHASING A SPRING STRIP TO PREDETERMINED FORM Filed Dec. 8, 1953 7 Sheets-Sheet 6 INVENTORS.

,Berrrar/JI' 14 47/13 y 1959 E. G. OTT ETAL DIE SET FOR SHAPING A SPRING STRIP To PREDETERMINED 7 Sheets- Sheet 7 Filed Dec. 8. 1955 I j INVEN;;S

r275 0 fierrrar f MZZ United States Patent DIE SET FOR SHAPING A SPRING STRIP TO PREDETERMINED FORM Ernst G. Ott and Bernard J. Wallis, Dearborn, Mich.,

assignors to American Metal Products Company, Detroit, Micln, a corporation of Michigan Application December 8, 1953, Serial No. 396,934

6 Claims. (Cl. 140-71) This invention relates to formed wire bending devices for undulated spring strips, and particularly to a die set for a formed wire spring strip which bends the strip into a substantially closed figure.

It has been the practice in the past to employ spring strips made of wire bent back and forth to provide like straight portions joined by uniform alternate left and righthand loops. The strips are bent at the ends into supporting portions which are attached to the frame to form a spring surface resiliently supported above the frame. Since the spring surface must assume a predetermined contour to provide comfortable seating, difficulty was always experienced when attempting to obtain such contour and comfort due to the fact that the loops and straight portions of the spring were of uniform construction. This was necessary in view of the type of machines heretofore employed for bending the wire into sinuous form around uniformly spaced pins, which thereby produced the uniform loops and straight portions.

The present invention pertains to a die set for bending a spring strip made of wire having laterally disposed torsion bars spaced the same or different distances apart by bendable side bars. The variation in the spacing of the torsion bars controls the contour and the comfort of the resulting seating surface. Such a spring is illustrated, described and claimed in the copending application of Hyland C. Flint et al. Serial No. 290,874, filed May 31, 1952, now Patent No. 2,659,121, and assigned to the assignee of the present invention. When employing such a spring in a back cushion, it is desirable to provide a support between the center of the resting portion of the spring and the frame. Such support after the die operation assumes the form of a closed figure and when assembled assumes somewhat of an oval shape.

A spring strip is first made straight by a suitable die set as disclosed in the folding link machine described in the patent to Richard J. Williams, issued on May 8, 1956 as Patent No. 2,744,546 and assigned to the assignee of the present invention. To form such a straight spring, the structure of the present invention is employed which is in the nature of a die set having an upper die element and a lower die element. The lower die element is provided with a pair of pinions operating on stationary racks for bending end lengths of the straight spring strip upon the downward movement of the press and strip. Certain of the side bars are bent a predetermined amount between the bent end lengths at the end of the stroke of the press, which forms a central curved portion between the bent ends which are directed inwardly thereover.

. Accordingly, the main objects of the invention are: to provide a die. set which forms a straight spring strip into a substantialy closed figure; to provide a die set having a pair of rotatable fingers which are rotated from operative position to permit the spring strip to be placed between the die elements and which rotate into engagement with the and lengths of the strips as the upper die element moves down to engage the lower die element, after which ice the two die elements and springs are moved downwardly together as the fingers are rotated to bend the end lengths a predetermined angular amount which extend over an arched central portion formed by bending the side bars upon the closing of the die set a predetermined angular amount; to form a closed figure from a straight spring strip in a die set which twists spaced torsion bars thereof to bend the end lengths of the strip to extend over the central portion which has side bars bent upon the closing of the die set to shape the central portion of the strip in the form of an arc, and, in general, to provide a die set which shapes a straight spring strip into a closed figure which is simple in construction, positive in operation, and economical of manufacture.

Other objects and features of novelty of the invention will be specifically pointed out or will become apparent when referring, for a better understanding of the invention, to the following description, taken in conjunction with the accompanying drawings, wherein:

Figure l is a plan view of a die set, with a portion of the top set broken away, embodying features of the present invention;

Fig. 2 is a sectional view of the structure illustrated in Fig. 1, taken on the line 2--2 thereof;

Fig. 3 is a sectional view of the die set illustrated in Fig. 1, taken on the line 3-3 thereof;

Fig. 4 is a sectional view of the structure illustrated in Fig. 1, taken on the line 44 thereof;

Fig. 5 is a broken sectional view of the structure illustrated in Fig. 1, taken on the line 55 thereof;

Fig. 6 is an enlarged, broken sectional view of the structure illustrated in Fig. 1, taken on the line 6-6 thereof;

Fig. 7 is a broken view of the structure illustrated in Fig. 2, with the die elements in separated position;

Fig. 8 is a plan view of the wire which is to be bent in the die set of the present invention;

Fig. 9 is a side view of the spring strip illustrated in Fig. 8 after the bending operation has been performed thereon;

Fig. 10 is a sectional view of the structure illustrated in Figs. 11 and 12, taken on the line 10-16 thereof;

Fig. 11 is a top plan view of the lower die element of the set, and

Fig. 12 is a bottom plan view of the upper die element of the set.

The diet set as illustrated in the figures embodies an upper die element 10 and a lower die element 11. The lower die element embodies a plate 12 having blocks 13 secured to the rear corners thereof for supporting the guide rods 14 which extend upwardly therefrom. A pair of end blocks 15 is secured to the base plate 12 by dowels 16 and screws 17. A lip 18 is provided on the upper edge of each of the blocks 15 for limiting the upward movement of the movable die portion 19 having the lip 20 on each end thereof. The movable die portion 19 has apertures 21 therein through which rack bars 22 extend for positioning the die portion on the plate 12. The rack bars are illustrated more specifically in Fig. 5 as embodying a rectangular block 23 secured to the base plate 12 by screws 24 when aligned by a dowel 2d. The block 23 carries the rack 26 secured thereon by screws 27 which are disposed in slots 28 that permit the racks 25 to be adjusted longitudinally. The bottom ends of the racks have a block 29 secured thereto by a screw 31 between which shims 32 may be added or removed for accurately locating the ends of the racks against shoulders 34 formed by slots in the face of the blocks 23. After this adjustment, the screws 27 are tightened to retain the racks in adjusted position.

The movable die portion 19 is retained on the base 12 for movement outwardly thereof an amount equal to the be inserted thereover.

ase gsee 3 spacing between the lips 20 and the lips 18 of the blocks 15. The movable die portion 19 has a central slot 36 in which the end lengths 37 of the Wire spring strip 38 may be swung when the ends are bent during the downward movement of the upper die element 10. At the end of the slots 36, the movable die portion 19 has a pair of centering blocks 39 secured thereto by screws 41. The blocks have a tapered, inwardly presenting arcuate face 42 the shape of the spring strip ends which are guided downwardly thereover when the spring strip is placed in the die set. A guide block 43 is mounted on the movable die portion 19 in alignment with a loop 44 of the spring strip 38 so as to center the spring strip between the faces 42 of the plates 39 when the die set is being loaded. When the spring strip is inserted between the die sets, the upper die set is in raised position, as well as the movable die portion 19 which is moved upwardly relative to the plate 12 by pressure rods 45 provided on the machine to function in the usual manner for raising the movable die portion 19 while permitting it to be moved downwardly by the downward movement of the upper die element 18. As illustrated in Fig. 1, eight of the pressure rods 45 are provided, engaging the movable die ele-.

ment 19. It is to be understood that any number of the rods more or less than eight could be employed.

Additionally to the raising of the upper die element and the movable die portion 19, slides 46, which support the bending mechanism 47, are also moved upwardly to clear the clamping block 48 to permit the spring strip to The slides 46 are slotted at 49 for receiving a pinion gear 51 for rotational movement. Each pinion gear is fastened to a stub shaft 52 which operates in bearings 53 extending in an aperture 54 through each slide 46. The stub shaft has a head 55 on the inner end which abuts against one side of the slide 46 when the opposite end is secured by a washer 56 and nuts 57. A slot 58 is provided on the face of the slide 46 which is adjacent to the protruding teeth portion 59 of the rack 26. The two slides 46 operate in rectangular apertures 61 in the movable die portion 19. An aperture 62 is provided in the bottom portion of the slides for receiving a spring 63. The opposite ends of the springs engage a recess in plates 64 which are secured to the movable die portion 19 by a plurality of screws 65. With this arrangement, after the movable die portion 19 is limited in its upward movement by the engagement of lips 20 with the lips 18 on the end blocks 15, the tension in the springs 63 moves the slides 46 upwardly and continues the rotation of the gear 51 and forming fingers 66 out of engagement with the holding block 48, as illustrated in Fig. 7. This provides clearance for the insertion of the spring strip 38 between the faces 42 of the centering blocks 39. As illustrated in Figs. 1, 2 and 4, three bending bars 67, 68 and 69 are mounted in slots 71 which extend inwardly into one side of the central slot 36 of the movable die portion 19. The bars are retained in the slots by a plate 72 which is secured over the slot ends by screws 73. The bars are limited in longitudinal movement by the overhanging head 74 at the top and the lips 75 provided at the bottom. Hardened striking plates 76 are mounted in recesses 77 in the base plate 12 and secured therein by screws 78. With such an arrangement, when the movable die portion 19 has been moved upwardly, the bending bars 67, 68 and 69 drop downwardly so that they will not interfere with the spring strip when extending thereacross. One or more blocks 79 may be provided on the opposite side of the slot 36 for supporting the side bars provided on the opposite edge of the spring strip. It is to be understood that when the side bars on the opposite side of the spring strip, or certain bars on both sides thereof, are to be bent, the left-hand side of the slot, as illustrated in Fig. 4, may be provided with the same or all of the bars 67, 68 and 69. It is to be understood that the blocks 79 are spaced from the bars 67, 68 and 69 so as not to interfere with the engagement 4 of the side bars therewith. Thus, when the die set is open, the bending bars are retracted and the bending fingers 66 are moved above the movable die portion to permit the spring strip 38 to be inserted between the die elements.

The upper die element 10 has a plate 81 to which guide blocks 82 are secured on the laterally extending arm portions 83 thereof. The blocks have a bushing 84 therein which engages the guide rods 14. Bending anvils 85, 86 and 87 are mounted on the end face of a block 88 aligned with the extending heads 74 of the bending bars 67, 68 and 69. The anvils and 87 have downwardly extending fingers 89 provided with tapered end portions 91 which first extend through loops of the spring strip 38 and shift the strip to accurately located position. The fingers 89 move downwardly adjacent to the locating blocks 48 and accurately position the torsion bars 92 of the spring strip on shoulders 93 of the blocks 48. The fingers 89, as illustrated in Figs. 6 and 7, have a projecting lip 94 which moves downwardly and clamps the bars 92 against the shoulders 93. A slot 95 is provided on the inner face of the finger 89 from which a plunger 96 is urged by a spring 97. The plunger passes over the bar 92 when unconfined during the downward movement of the finger 89 but engages the bars 92 after the bending operation and carries the bars and the formed spring upwardly out of the lower die element when the die element 10 is moved upwardly. The spring which is now formed and held betweenthe fingers 89 is stripped therefrom by the stripping fingers 98 which are secured to the movable die portion 19 on Z-shaped brackets 99. On the final upward movement of the die element 10, the stripping fingers 98 engage the torsion bars 92 and cause them to move downwardly off of the fingers 89, thereby releasing the formed spring from the die set.

After the die set is secured in a press, the opening of the press raises the die element 10 and permits the movable die portion 19 to be raised by the plurality of rods 45, after which the two forming fingers 66 are rotated and moved upwardly away from forming position. This permits a spring strip 38 to be inserted in desired position between the die elements, being guided over the block 43 to have the ends located adjacent to the faces 42. Upon the downward movement of the upper die element 10, the fingers 89 moving downwardly accurately center the spring strip and clamp the two torsion bars 92 which are to be twisted between the shoulder 93 and the lip 94, as clearly illustrated in Fig. 6. During this aligning movement, the slides 46 are engaged by blocks 101 secured to the upper die element, as illustrated in Fig. 3, to produce the downward movement of the slides 46 and the rotation of the gear 51 and finger 66. When the slides 46 engage the plates 64, the movable die portion 19 and the spring 38 are carried downwardly therewith, with the torsion bars 92 disposed on the center lines of the gears 51. The contmued downward movement and rotation of the gears 51 by the teeth 59 of the rack 26 causes the fingers 66 to rotate the spring end lengths 37 inwardly toward each other, as illustrated in Fig. 2. Preferably the end lengths are rotated to the position illustrated in solid line, in Fig. 2, from whichthey will spring back to the dot and dash line positions indicated by numeral 102. Near the end of the downward movement, the bending bars 67, 68 and 69 engage the blocks 76 and are retained stationary as the anvils 85, 86 and 87 on the upper die element continue to move downwardly and thereby bend the side bars 103, 104 and 105 angularly on the bending heads 74, as illustrated in the figures. After the upper die element 10 reaches the bottom of its stroke, the die element is moved upwardly to initial open position, near the end of which the stripping fingers 98 engage the torsion bars 92 and thereby strip the formed spring strip from the fingers 89 before the upper die element reaches the end of its upward movement. The formed strip may then be removed from between the upper and lower die elements and 11 and a new spring strip to be bent inserted therein.

In Fig. 8 the spring strip is illustrated before the bending operation has been performed thereon, and in Fig. 9 the spring strip is illustrated after the bending operation to have it formed so that it may act as a spring support for the load carrying portion of the spring strips provided in the back cushion.

Referring to Fig. 10, a further form of the invention is illustrated, that wherein the rack and pinion are carried by the die plate 111 of the upper die element 10. The lower die element has a bottom plate 112 which is retained in aligned relation with the plate 111 by a pair of guide bars 113, only one of which is illustrated. The lower die plate 112 supports a movable die portion 114 which is guided upon a plurality of guide bars 115, only one of which is shown in the figure. The movable die portion 114 is otherwise similar to the die portion 19 of Fig. 2, having the bending bars 67, 68 and 69 supported for lengthwise movement by the plate 72. The upper die plate 111 carries the anvils 85, 86 and 87 which cooperate with the bars 67, 68 and 69 to bend the bendable bars 103, 104 and 105 of the spring strip.

The plate 112 supports a pair of blocks 116 on each of which an upstanding cylindrical block 117 is welded. The blocks 117 support cylindrical striking heads 118 which are secured thereto by a bolt 119. Shims 121 between the blocks 117 and heads 118 accurately position the tops of the heads 118 to thereby control the initial turning movement of the fingers 66. The upper die plate carries a pair of blocks 122 in each of which a gear 123 is secured on a shaft 124. The teeth of the gear 123 of each block 122 mesh with the teeth of a gear 125 on which the finger 66 is secured. Each block has an aperture 126 containing a bearing sleeve 127 in which a rack bar 128 is axially movable. The bar 128 has an aperture 129 for receiving a portion of a spring 131, the other portion being contained within an aperture 132 in the plate 111. Rack teeth 133 on the rack bar 128 and in meshing relation with the teeth of the gear 123. By using the intermediate gear 123 between the rack bar 128 and gear 125, the rotation of the latter gear will be in the same direction as the gear 51 of the structure illustrated in Fig. 2 when the die set is relatively moved.

When the die set is in open position, the die portion 114 is raised by the pluralitty of pressure rods 45 so that its top surface is entirely clear of the rack and the component parts thereof. This is desirable when automatic feeding and ejecting mechanism is employed for the spring strips, before and after the bending thereof. In the structure of Figs. 1 to 7 above described, the rack bar extended between the separated die elements and interfered with the proper locating and ejection of the formed strip when the automatic feeding and ejecting mechanism was added. When the upper die element is in raised position, the spring 131 is extended and the rack bar 128 is supported on a ledge 134 at the bottom of the aperture 126. The finger 66 has been returned to its initial position ready to engage the spring strip end 37 as the upper die element is moved downwardly. When the finger has moved into engagement with the end to be bent, the rack bar 128 strikes the top surface of the head 118 and the gears 123 and 125 are rotated as the die set continues to close. During this closing movement, the rack bars 128 are maintained stationary while the blocks 122, carrying the gears, move downwardly therewith, thereby producing the rotation of the gears and fingers 66. Near the end of the closing movement, the bending bars 67, 68 and 69 strike the hardened plates 76 located within recesses in the plate 112 and are held against further downward movement so as to project above the movable die portion 114 as the latter portion continues to move downwardly. The bending bars bend the bars 103, 104 and 105 of the spring strip through the cooperation of the anvils 85, 86 and 87 therewith. It is to be understood that the rack and gear structure on the right-hand side of the plate 111, as illustrated in Fig. 10, produces the bending of the end portion 37 of the spring strip as the rack and gears on the left-hand side bend the end 102.

To simplify the location of the strips, the end blocks 136 which support the anvil portions and 87 have sloping fingers 137 which form inverted V-shaped slots for receiving and locating the torsion bars 92 in grooves 141 along which twisting occurs to produce the bending of the ends. The grooves 141 are disposed in blocks 142 which have one portion secured to the block 114 and the portion containing the groove extending within an elon gated slot 143 located in the central portion of the block 114. The portion of the blocks 142 extending within the groove 143 has a slot 144 therein which permits the fingers 137 to pass downwardly thereinto; through the space 145 between ejecting fingers 98 as the upper die portion is moved upwardly. A plunger 96 projecting from each of the blocks 136 retains the formed spring strip between the blocks until near the end of the upward movement of the upper die plate 111. During such movement, the gear 123 is rotated counterclockwise due to the fixed position of the rack bar 128, it being maintained against the head 118 by the spring 131 until the finger 66 returns to its initial position, at which time the rack bar 128 separates from the head 118 as it now rests upon the ledge 134 to be carried upwardly with the die plate 111. The striking of the torsion bars 92 against the ends of the finger 98 strips the formed spring from the, blocks 136 as the die plate 111 moves upwardly. An ejecting mechanism (not illustrated) removes the formed spring from between the die set. While the bending bars 67, 6S and 69 are herein illustrated for bending the side bars on one side of the strip, additional bending bars 146, 147 and 148, cooperating with anvils 149, 150 and 151, are provided for bending certain of the side bars of the spring strip on the opposite side thereof. When the spring 38 is placed on top of the projecting portion of the blocks 142, the end portions mate with the contoured face 152 of the blocks 153 which are mounted on the block 114. The contoured faces 152 accurately locate the length of the spring relative to the projecting portion of the blocks 142.

The loading mechanism meanwhile has inserted a new spring strip between the die set and the downward movement of the die plate 111 accurately locates and clamps the torsion bars 92, at which time the gears 123 and 125 are rotated, as the downward movement of the rack bars 128 is interrupted, to rotate the fingers 66 and bend the spring end portions 102 and 37. It will thus be seen that the die set illustrated in Fig. 10 is substantially the same as that illustrated in Fig. 2, with the exception that the gears and rack bar are carried by the upper die plate 111 to prevent them from being present between the die set when in open position, as occurs in the structure illustrated in Fig. 2. Otherwise, the operation on the spring in either of the die sets is exactly the same.

What is claimed is:

1. In a die set for bending a spring strip, an upper die element, a lower die element, supporting means for said die elements which permit the upper die element to move into engagement with said spring strip which is adapted to seat upon the lower die element and then to be moved along therewith, rack bar means, means on said supporting means for retaining said rack bar means stationary, gear means on one of said die elements operated by the rack bar means after said upper die element has moved into engagement with the spring strip and during the movement of the die elements together, a bending finger in operative engagement with said gear means for rotation thereby, means nonrotatively retaining said gear means relative to said rack bar means as said upper die element is moved toward said lower die element, and means causing said gear means to be rotated by said rack bar means during the simultaneous movement of the die elements.

2. In a die set for bending the wire of a spring strip having transverse bars joined by longitudinal bar's, said die set embodying an upper die element, a lower die element, supporting means for said die elements which permit the upper die element to move into engagement with said spring strip which is adapted to rest upon the lower die element and then to be moved along therewith, rack bar means, means on said supporting means for retain ing said rack bar means stationary, gear means on one of said die elements operated by the rack bar means after said upper die element has moved into engagement with the spring strip and during the movement of the die elements together, a bending finger in operative engagement with said gear means for rotation thereby, means retaining said gear means nonrotatively relative to said rack bar means as said upper die element is moved toward said lower die element, means causing said gear means to be rotated by said rack bar means during the simultaneous movement of the die elements, clamping means on the upper die element, and a support on the lower die element on which a transverse bar of the spring strip is secured by said clamping means upon the engagement of said die element, said transverse bar being clamped on the center about which said bending finger is rotated.

3. In a die set for bending a wire spring strip having transverse bars joined by longitudinal bars, said die set embodying an upper die element, a lower die element, supporting means for said die elements which permit the upper die element to move into engagement with said spring strip which is adapted to rest upon the lower die element and then to be moved along therewith, rack bar means, means on said supporting means for retaining said rack bar means stationary, gear means on one of said die elements operated by the rack bar means after said upper die element has moved into engagement with the spring strip and during the movement of the die elements together, a bending finger in operative engagement with said gear means for rotation thereby, means for nonrotatively retaining the gear means relative to said rack bar means as said upper die element is moved toward said lower die element, means causing said gear means to be rotated by said rack bar means during the simultaneous movement of the die elements, clamping means on the upper die element, a support on the lower die element on which a transverse bar of the spring strip is secured by said clamping means upon the engagement of said die element, said transverse bar being clamped on the center about which said bending finger is rotated, and means on said clamping means for carrying said bent spring strip upwardly therewith when the die elements separate during the upward movement of the upper die element.

4. In a die set for bending a wire spring strip having transverse bars joined by longitudinal bars, said die set embodying an upper die element, a lower die element, a support for said die elements which permits the upper die element to move toward the lower die element and then move as a unit therewith, means between said die elements for clamping a transverse bar of the spring strip when the die elements are moved into engagement with the spring strip, a rack and pinion mounted on said die elements, a rotatable bending finger on said die elements having the center of rotation aligned with the transverse bar and operated by the rotation of said pinion for engaging a longitudinal bar adjacent to said clamped transverse bar, and means for operating said rack and pinion to rotate the pinion only after said die elements have moved into engagement with the spring strip.

5. In a die set for bending a wire spring strip having transverse and longitudinal bars, comprising an upper die element, a lower die element, a support for said die elements which permits them to move together when the upper die element has been moved downwardly into engagement with said spring strip which is adapted to rest upon the lower die element, clamping means on said die elements for locating and securing spaced transverse bars of said spring strip between said die elements, bending means on said die elements for engaging the longitudinal bars which are located adjacent to said transverse bars, and means on said die elements for angularly moving said longitudinal bars and twisting said transverse bars after the upper die element has moved into engagement with the spring strip and during the simultaneous movement of said die elements.

6. in a die set for bending a wire spring strip having transverse and longitudinal bars, comprising an upper die element, a lower die element, a support for said die elements which permits them to move together when the upper die element has been moved downwardly into engagement with said spring strip which is adapted to rest upon the lower die element, clamping means on said die elements for locating and securing spaced transverse bars of said spring strip between said die elements, bending means on said die elements for engaging the longitudinal bars which are located adjacent to said transverse bars, means on said die elements for angularly moving said longitudinal bars and twisting said transverse bars after the upper die element has moved into engagement with the spring strip and during the simultaneous movement of said die elements, anvils on said support in position to engage certain of the longitudinal bars in the central portion of the spring strip, and blocks carried by said upper die element aligned with the anvils for bending the longitudinal bars engaged thereby.

References Cited in the file of this patent UNITED STATES PATENTS 

